Physics Lab #11

Uniform Circular Motion: Conical Pendulum

Theory

I demonstrated the conical pendulum in class on a couple of occasions.  You now have the theoretical background to derive the period of such a pendulum as a function of the height of the pendulum (the height would be the horizontal distance from the point you are holding the string to the height of the revolving mass and will be called h below).  You can derive the formula for the period by using the force triangle I gave in class yesterday as well as the similar triangle involving the radius of the circular motion, r, the height, h and the length of the string, l.  (This method is similar to the one we used to find the formula for the centripetal acceleration.)  You should derive the formula prior to the lab.

 Procedure

1.      Come up with your own best method to get the data for the table below.  Be sure to describe the method fully in the procedure of the write-up.

2.      Figure out what you need to graph according to the equation you derived in the theory section.  Graph it and use the results to find the acceleration due to gravity.